Number displaying device



April 1942- J. w. BRYCE NUMBER DISPLAYING DEVICE Filed April 10, 1940 7Sheets-Sheet 2 F IG.3.

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v WATTORNEKS April 28, 1942. J w BRYCE I 2,281,350

NUMBER DISPLAYING DEVICE Filed April 10, 1940 7 Sheets-Sheet 3 19 FIG.6. w

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NUMBER DISPLAYING DEVICE Filed April 10, 1940 7 Sheets-Sheet 4 FIG. 9a.

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BY j/ vii ATTORNEYJ April 28, 1942. w, BRYCE 2,281,350

NUMBER DISPLAYING DEVICE Filed April 10, 1940 7 Sheets-Sheet 5 I NV ENTOR.

ATTORNEY! April 28, 1942. J w BRYCE 2,281,350 NUMBER DISPLAYING DEVICEFiled April 10, ,1940 7 sheets-sheets TTTTTTT W .Z MAM/W ATTORNEYS April1942- J. w. BRYCE 2,281,350

NUMBER DISPLAYING DEVICE Filed April 10, 1940 '7 Sheets-She'et '7F'IGJZ.

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ATTORNEY.

Patented Apr. 28, 1942 NUMBER DISPLAYING DEVICE James W. Bryce, GlenRidge, N. J., assignor to International Business Machines Corporation,New York, N. Y., a corporation or New York Application April 10, 1940,Serial No. 328,850

8 Claims.

This invention is an improvement upon the device shown and described inthe copending application of R. I. Roth, Serial No. 313,062, filedJanuary 9, 1940. Here there was shown and described a display devicewherein cathode ray tubes were utilized for displaying numbers at remotepoints from a control station! Ac- I cording to the previous invention,each display apparatus comprised a plurality of cathode-ray tubes, onefor each denominational order. One tube was used for units order, onefor the tens order and one for the hundreds order.

The present invention is directed to and has for its objects animprovement and simplification of the foregoing device to the generalend that a single cathode ray tube may be utilized to display aplurality of digits upon a common screen in a single tube. In this wayfor a three order displaydevice only a single tube is required insteadof three separate tubes as heretofore. In general the number of tubes iscut down by modifying the pattern component emitter unit so far as thetrack configuration is concerned. According to the previous invention adisk was provided which was scanned by photo-electric cells and thisdiskhad successive segments or zones allotted to the different digits ofthe digital series.

According to the present invention the disk is changed in configurationwhereby what may be termed the digit zone is further sub-divided intoidentical sub-zones. Thus during rotation of the disk on scanning thefirst sub-zone the related digit may be displayed on the cathode raytube. Then on scanning the second subzone, the digit is re-traced on thesame cathode ray tube screen and so on for the third subzone. With suchrepeat scanning and without further controls, it is obvious that thethree same digits would be traced at the same area on the cathode raytube screen and the efiect would be to give a single display of a singledigit only. To provide for multiple display on a single screen of asingle tube, supplementary controls are provided so that varying controlbiasing voltages are superimposed so to speak upon the tracing voltageswhereby a digit will be first displayedin aleft hand zone on the screenand thereafter the same digit will be displayed in the middle zone ofthe screen of the same tube and thereafter the same digit will bedisplayed in a third zone of the same tube. It will be appreciated thatby such an arrangement it will be possible to display the same digits inthree difierent places ona common cathode ray tube on ppended. claims.-

screen. Thus one could have a display of 111, 222, 333', etc. However,in practice such an arrangement would be of little utility andaccordingly further controls are provided so that-it is possible toconcurrently display different digits on a single screen of one tube. Itmay be mentioned that the display of a digit in one area occurs ata'slightly different time than a display of a like or difierent digitupon another area of the screen of a single tube, but due to the highrotational speed which is employed in driving the disk, the repeatedtracing occurs in such rapid recurrence that the effect is a concurrentdisplay in all threefields.

Accordingly, the object of the present invention resides in theprovision of means to dis play a character or characters in differentlateral zones upon the screen of a cathode ray tube.

A further object resides in the provision of novel biasing controls andtiming controls to cause display in difierent lateral zones to beeffected successively.

A further object of the present invention resides in the provision of asimplified control device for providing the tracing potentials whereby aplurality of diiferent or like characters may be displayed at differentzones of a tube or tubes thereby enabling the number of tubes to bereduced.

A further object of the present invention resides in the provision of acathode ray tube character displaying device wherein a plurality ofdifferent or like characters may be displayed companying specificationand claims and shown in the drawings which show by way of and what I nowconsider to be the best mode in which I have contemplated applying thatprinciple. Other embodiments of the invention employing the same orequivalent principle may be used and structural changes made as desiredby those skilled in the art without departing from the presentinvention'and within the spirit of the In the drawings:

Figure 1 is a perspective diagrammatic view of the complete systemshowing several distant indlcators, a controlling keyboard and acomponent emitter unit, together with amplifiers and associated parts;

Fig. 2 is a partly side elevational view and partly sectional view ofthe keyboard section of the apparatus;

Fig. 2a is a detail view of one pair of key controlled contact devices.the view being taken substantially on line la-2a of Fig. 2 and lookingin the direction of the arrows;

Fig. 2b is an enlarged view of certain contacts shown in smaller scaleon Fig. 2; Fig. 3 is a top view of the control apparatuswith the coverremoved to show the parts within the housing;

Fig. 4 is a detail sectional view taken on line 4-4 of Fig. 3;

Fig. 5 is an end view of the part of the apps ratus shown in Fig. 4, theview being taken on line 55 of Fig. 4 and looking in the direction ofthe arrows;

Fig. 6 is a diagrammatic graph view showing plotting points for thecharacter i; I

Figs. 7 and 8 are enlarged details of portions of certain segmentsections of the disk shown in smaller scale in Fig. 5;

Figs. 9a and 9b taken together with Fig. 9b to the right of Fig. So asindicated in diagrammatic view, Fig. 14, show the complete circuitdiagram of the apparatus which constitutes one embodiment of theinvention;

Figs. 9m. and 9!) taken together with Fig, 9b' to the right of Fig. Qaaas indicated in diagram matic view, Fig. 15, show the complete circuitdiagram of the apparatus constituting a modified embodiment of theinvention Fig. 10 is a commutator timing diagram of the apparatus whichcomprises the main embodiment of the invention;

Fig. 10cc. is the commutator timing diagram of the apparatus whichcomprises the modified embodiment of the invention;

Figs. 11 and 12 are views similar to Figs. 7 and 8 but show enlargeddetails of certain segment sections or the disk which are used in themodified embodiment of the invention;

Fig. 13 is a top plan view similar to Fig. 3 but showing the controlapparatus utilized for the modified embodiment of the invention; and

Figs. 14 and 15 are diagrammatic views showing the manner in which thecircuit diagram sheets are to beplaced together for the main andmodified embodiments.

Before describing the system in detail, it may be stated to compriseseveral display units, a control apparatus and a. selecting unit in theform of a keyboard. Each display unit comprises a single cathode raytube and provision is made so that the single tube can concurrentlydisplay several digit characters. In the present embodiment each cathoderay tube of each display unit is capable of displaying three orders ofdig= its. The other parts of the system include a simplified form ofpattern component emitter These timing selectors are brought intooperation and kept out of operation under the control of th keyboardunit. An operator or the keyboard unit, it it is desired to transmit toon or more distant points number indications such as a. call number, maydepress the proper number keys on the keyboard and this will bring aboutsuch control that all of the distant display units will concurrentlydisplay the same numbers. Provision is made for a steady display ofnumber or for a flashing display or numbers as desired.

In more detail, referring first to Figs. 2, 2a. and 2b, 20 generallydesignates the keyboard unit. It is of th conventional 81 key type, butfor simplicity of illustration, only three columns 01 keys have beenshown. The keys 2| are guided for vertical movement by means orperforated plates 22. They are spring retracted upwardly by springs 23.The keys are latched down in the customary way by detent members carriedon detent bars such as 26. The keyboard is or the flexible type and arelease key 21 is provided which, upon depression, shifts all of the bar26 and releases all of the keys. Each key at its bottom carries aninsulated portion 21a which in turn carries a V-shaped contact member28. Upon depression of any key, the contact member 28 establishescontact with a contact member 29 carried on a bar 30 and with anindividual contact member 3| carried on an insulating support 82.

GENERAL Crrsasornnrsrrcs or Gs'rrroon RAY Tunas Before describing thedetails of the indicating device and the control therefor, certaingeneral characteristics of cathode ray tubes which are used in thedistant indicator will be briefly described. Several typical andsuitable cathode ray tubes are illustrated diagrammatically on thecircuit diagram (Fig. 9b). Each tube comprises an evacuated body intowhich extends a heater element H. Associated with the heater element isa cathode l2 providing a source of electrons. Also in theevacuated bodyand disposed in the order from left to right are a grid i3,an anodenumber 1 designated it, an anode number "2 designated l5, and two pairsof deflector plates or electron deflection control elements. The upperand lower vertical deflector plates are respectively designated YU andYL and the horizontal deflector plates are respectively designated XLand KR. XL signifies horizontal deflection to the left and KR signifieshorizontal deflection to the right. YU signifies upward verticaldeflection and YL signifies lower or downward vertical deflection. Theright hand end of the cathode ray tube includes the usual fluorescentscreened end It. The Y deflector plates are plates above and below thecenter axis of the tube. The X deflector plates are disposed to theright and left of the center axis of the tube.

In operation of a cathode ray tube, if no potential is applied to eithersets of plates, the stream of electrons will be emitted along thecentral axis of the tube and impinge on the fluorescent screen It at thecenter of the screen. If, however, the potential on the horizontal andverticaldeflecting plates is changed, the stream of electrons can bedeflected either upwardly or downwardly or to the right or to the leftor in combined resultant directions. Changing relative potential on theY set of plates will bring the stream of electrons up ordown andsimilarly changing the relative potential on the X plates will directthe stream of electrons alternatively to the right or left. By providingproper potential and proper changing potential over a period of time onboth sets of plates any desired. figure or figures or character orcharacterscan be tracedand properly displayed on the fluorescent screenIt. By

repeatedly tracing the beam of electrons to the proper points or areasof the screen, an image can be produced which can be visibly read in theday time or at night. Cathode ray tubes are adapted to operate anddeflect electron beams at an exceedingly high frequency.- They mayaccordingly be termed inertia free image tracing devices. Such devicesfurthermore require a mere change of voltage on the plates to deflectthe electron stream and current consumption is negligible. This lowcurrent consumption adapts these tubes for use as indicators at aconsiderable distance from the control point. Control of brilliance isafforded by applying proper potential to the grid l3. Grid I3 is alwaysnegative with respect to the cathode l2 and by decreasing the negativebias on grid 13, brilliance can be increased. By increasing the negativepotential upon grid I3 the beam impingement upon the screen can bewholly suppressed.

Anode number 1 designated i4 is used to control the focus of the beamupon the screen. Anode #1 is always positive with respect to the cathodel2 and a variable resistance device 15- 16 can be adjusted to afford theproper potential to sharply focus the beam on the screen 16. Anode #2designated I5 is the conventional accelerating anode used in cathode raytube devices of this class.

Having generally described the characteristics of the cathode ray tubesthere will now be described one manner of providing the deflectingvoltages which control the movements of the electron beams for tracingthe images upon the various cathode ray tube screens.

Pattern component emitter unit 33 in Fig. 1 designates a box whichcontains both the pattern component emitter unit and certain amplifyingapparatus. Mounted within this box (see Fig. 3) there is a driving motor35. This motor by the gearing shown is adapted to drive a shaft 31.which is suitably mounted for rotation. The shaft 31 is adapted to drivetwo sets of commutator devices. The right hand set of commutatorscomprises ten commutators, one of which commutators is designated 38 inFig. 3. Each of these commutators (see Figs. 9a and 10) comprises aninsulated portion over the greater portion of the periphery of thecommutator with a conducting portion at a single point upon thecommutator. Trailing on the periphery of each commutator 38 is a pair ofbrushes which are designated 39 on Fig. 3. The conducting segments onthe different commutators of the right hand set are so arranged to closeat different angular positions of rotation of the shaft 31 as will bereadily understood by inspection of Fig. 9a and the commutator timingdiagram Fig. 10. The purpose of these commutators and their timing willbe subsequently explained.

Referring now to the left hand group of com-v mutators, this set ofcommutators comprises six commutators which are respectively designated38a, 38b, 38c, 38d, 38c and 38f. The left hand set of commutators eachhave ten sets of conducting portions as will be apparent from the timingdiagram (Fig. 10) Trailing on these conducting portions are pairs ofbrushes, one pair of which is designated 39a in Fig. 3. The purpose ofthis left hand set of commutators and their timing will be subsequentlyfurther explained.

Again referring to Figs. 3 and 4, the shaft 31 is also adapted to driveand rotate an element such as a disk 40; This disk 40 (see also Fig. 5)is generally transparent, but it is provided with two opaque concentrictracks 40X and MY. To

direct light to these tracks a pair of light sources are provided. .Eachsource of light preferably includes a lamp 4| (see Fig. 4) within a lampbox 42. A suitable reflector 43 directs the light from the lamp througha lens system 44 and through an apertured diaphagm 45 so that-the lightis directed and concentrated onto and through the related partiallyopaque track. One light source directs light to and through the 40Xtrackand the other light source directs light to and through the 40Ytrack. Upon the opposite side of the disk 40 from the light source thereare provided two photo-cells which are respectively designated 46X andMY.

It may be explained that if the width of one of the tracks such as 40Xis varied at different angular positions. around the disk 40, differentamounts of light will be allowed to pass to the photo-cell 46X uponrotation of the disk. This variable illumination will vary the currentand/or voltage output in a circuit controlled by this particularphoto-cell. The photo-cells act to al. low more or less current to flowin their output circuits depending upon the amount of light which theyreceive.

Referring again to Fig. 5 it will be noted that the disk 40 is shown asdivided up into segment portions each of which has a designating figuresuch as 0, l, 2, etc. up to 9.

Referring to Figs. 5, 7 and 8, it will be further noted that eachnumbered segment section is further divided into sub-sections. The .7section, for example, is divided into three identical sub-sections whichare respectively designated 1a, 1b and 10 on Fig. '7. It may beexplained that the 40X track for a given sub-section such as 1a willprovide a variable amount of light to infiuence the related photocell46X whereby it supplies changes in potential and component voltages tothe X plate of the.cathode ray tube or tubes'for effecting horizontaldeflection for tracing the character 1. Similarly, the .40Y track forthe related sub-segment section Ia controls the Y photocell whereby theproper changing potential is applied to the Y plate to effectvertical'deflection for tracing the character '7. As the disk rotatesfurther and traverses the lb section there will be a repeated generationof the voltage for tracing the character '7. Likewise there will be arepeated voltage generation on traversing the 10 section.

Inasmuch as the two lamp sources for the different tracks are degreesapart, the related sections of the opaque tracks are-similarly displaced180 degrees with reference to one another for a corresponding digit.This 180 degrees relation of the tracks is shownin Figs. 7' and 8. Theoutside track of Fig. 7 is the track for repeatedly controlling thechanging potential on the X plates for tracing the digit 7. The insidetrack on Fig. 8 on the other hand, is the track for controlling thechanging potential on the Y plates for tracing the digit 7. q

The manner of laying out the various sub-segment sections of the diskwill now be explained.

Referring to Fig. 6, on this figure, the outlines of the numeral 7 havebeen laid out. The numeral 7 has been divided into a set of sections ofequal length, this particular character being divided into sections I to3I inclusive. -In order to trace the electron beam for the upperhorizontal part of the character 7 the Y component voltage should bemaintained constant while points I to I3 are traced. If the inner track(for controlling the Y potential) on Fig. 8 be examined it will be foundthat the IOY track has a constant maximum width for all points from I toI3 inclusive. Thereafter for further points along the figure 7 (see Fig.6) the tracing beam should be caused to both descend and move to theleft. To cause descent of the beam there is a gradual diminution of thewidth of the IOY track from point I3 (Fig. 8) back to point 3I. Itwill'be understood that the NY track has a like configuration insections 1b and 1c.

Referring now to the 40X track (Fig. '7) the X component at point I is0. From this point I to point I3, the 40X track gradually increases inwidth as indicated on Fig. 7, see sub-segment section Ia. From point I3back to point 3|, the

40X track progressivel diminishes in width.

Referring to Fig. 7, it will be noted tat'there is a zone allotted frompoint 3| to point I. This point, as for example, point I9, the Yordinate distan-ce on Fig. 6 between the X axis and point I9 isdetermined. This distance is then multiplied by a constant, the value ofwhich is to be determined in a manner to be subsequently explained. Theresulting amount .will give the width of the Y track at point I9 on thedisk.

The constant above referred to is the ratio of a predetermined arbitrarymaximum width of the Y track on the disk with respect to the maximumordinate value for the character in Fig. 6. This arbitrary value dependsupon the circuit relations and characteristics of the photocells andamplifier tubes which are used in connection with the track. i

The width of the X" track at point I9 is the X abscissa distance betweenthe Y axis and point I9 multiplied by another constant. This constant isthe ratio'of the predetermined arbitrary maximum width of the X trackwith respect to the maximum abscissa value for the character in Fig. 6.This arbitrary value again depends upon the circuit relations andcharacteristics of the photo-cells and amplifier circuits.

Fig. shows the configuration of the X and Y tracks for controllingrelated photo-cells so that the cathode ray tube or tubes willsuccessively display all of the different digits of a set, i. e. from 1to 9 and 0 inclusive, and for also providing repetition of display of aparticular single digit. In other words, taking for example thecharacter 7 it is possible to display this digit '7, three times insuccession. Such display of this same digit may be effected upon threedifferent portions of the screen of a single tube. Each complete trackis divided into a number of main segment sections, one main segmentsection for each difierent digit. Each main segment section is dividedinto three sub-segment sections for the same digit. The main segments ofboth tracks are shown numbered-with digits which comprise the digitdisplayed by the cathode ray tubes when that particular main segment isbeing scanned by the photo cells. As shown in Fig. 5, the 46X photocellis scanning the -1 main segment of the X main segment of the NY track.The difierent main segments related to different digits are scanned insuccession and the difierent sub-sections of each main section are alsoscanned in succession. It will be noted that the successive main segmentsections do not follow the successive order of the digits. However, theycan be transposed in position on the disk to follow the order of thedigits or they can be indiscriminately arranged as shown.

With the disk 40 in continuous counterclockwise rotation, the 46Xphoto-cell will receive varying amounts of illumination as tosuccessively afiord changing potential for first tracing the outline ofthe character 1, then repeating the tracing of the outline of thecharacter 1 twice and then .as the next segment is reached the character9 in repetition and so on. Then for the next main segment, the character6 repeatedly, then 3 repeatedly, then 2 repeatedly, 4 repeatedly, 5-repeatedly, 7 repeatedly, 0 repeatedly and 8 repeatedly and thenrecurring with the character 1. The other photo-cell 46Y will, uponrotation of the disk 40 from the position shown, first trace thecharacter 1 three times in succession, then 9, three times, then 6 threetimes, then 3 three times, then 2 three times, then 4. three times, then5, 7, 0 and 8 three times and then repeat with 1 again.

From the foregoing explanation, it will be understood that if both lightsources were on and both photo-cells were in circuit through certainamplifiers for a given cathode ray tube, as the disk 40 rotates throughone complete revolution all of the various characters comprising thedigits 1 to 9 inclusive and 0 would be successively traced on a cathoderay tube screen. Furthermore, each character would berepeatedly tracedthree times on movement of the disk through the three difierentsub-segment sections. The order of succession in which the diflerentcharacters are traced by any one tube would be 111, 9--9-9,

' or at the right of the screen. In other words,

track while the NY photo-cell is scanning the l the control is such thatif a single character such as 1 is to be repeatedly traced, the positionof display can be made to vary laterally with respect to each successivetracing.

It may be mentioned that the disk 40 is rotated extremely rapidly andthe rate of rotation is such that a visual image will be displayed whichcan be seen even if the cathode ray tube is operative only for onesub-segment position of I the disk. To provide for such singlesub-segment section visual display the commutator devices 38, 38a, 38b,38c, 38d, 38c and 38f are provided. The selective control aflorded bythese commutators will be more fully explained hereinafter, but it maybe stated generally that the 38 commutators effect segment selection ofthe main segment sections, whereas the left hand set of commutatorseffect sub-segment selection.

The disk device just described constitutes what might be termed apattern component emitter unit and if such disk is maintained in a stateof rotation at relatively high speed it will be appreciated that suchdisk can be used to progressively vary the X component voltages and theY'component' voltages which are applied to the deflecting plates of. thecathode ray tube or tubes to afford display of one or more charactersand to also afford display of a single character repeatedly. It may befurther explained that a single disk unit can be utilized forcontrolling one or more cathode ray tubes.

Before describing the commutator and switching control for the variouscathode ray tubes, the amplifier circuits for the photo-cells will beexplained.

Photo-cell and amplifier units accordance with the variations of lightimpressed on the photo-cells.

Consider, for example, photo-cell 46X (Fig. 9a) which is utilized to"control the horizontal deflection of the cathode ray beam in one or moreof the cathoderay tubes. Such photo-cell Mix is connected in series witha battery 50 and a resistor whereby the diflerence of potential acrossthe resistor varies in accordance with the illumination of thephoto-cell. The grid cathode circuit of a vacuum tube 52 convenientlybiased negative at all times by the battery 53 includes a portion of theresistor 5| preliminarily adjustableby a contact 54 on the resistor. Theplate cathode circuit of "the tube 52 includes aB battery or othersource of direct current 55 and a resistor 56 in series ther'withintermediate the positive side of the battery 55 and the plate of thetube 52. For impressing a proper voltage across the horizontaldeflecting plates XL and X8. of the cathoderay tubes which are connectedto the terminals 51 and 58 of the amplifier unit, three sets of biasingnetworks are provided, the first biasing network comprises a resistor5911 connected across a source of voltage preferably comprising seriesconnected batteries 60a and Ma. The conductor intermediate batteries 80aand Gla is connected through a circuit established by the 38a commutatorto a preliminarily adjustable contact tap 62 on the resistor 58, Theterminals 51 and 58 are respectively connected to a preliminarlyadjustable contact tap 63a 00- 0 operating with the resistor 59a and tothe positive side of the battery 55, i. e. the positive end of theresistor 56..

As explained before, there are three sets of biasing'networks. Thesecond network includes resistor 59b, tap 63b, series connectedbatteries 60b and Gib with the circuit connection between the batteriesextending to the commutator 38b.

The commutator circuit is completed back to con-,

tact tap 62. The .other and last biasing network comprises resistor 59c,tap 63c, batteries 60c and Blc. ,The midpoint between these-batteriesconnects back to commutator 380, the commutator circuit again beingcompletedto tap 62.

As will be noted from the timing diagram (Fig. 10) commutators 38a to380 close in succession. The biasing relations (if the respectivenetworks are such that with commutator 38a closing the numeral will bedisplayed on the left of the oathode ray tube. On the other hand if the38b commutator closes its biasing circuit the numeral will 'be displayedin the center of the tube, whereas with the 380 commutator closing, thenumeral will bedisplayed on the right of the cathode ray tube screen.Obviously the relations could be changed as desired.

It will now be seen that if the photo-cell 46X receives illumination ora predetermined inaximum illumination the grid of the tube 52 will havea predetermined maximum negative bias. The contact arms 54, 62, 63a, 63band 630 are conveniently so adjusted (in a manner whichwill be readilyunderstood by those familiar with the art) that for this maximumillumination of the photo-cell Mix the resulting maximum negative biason the grid on the tube 52 will be such that the output voltage betweenthe terminals 51 and 58 will maintain the electron beam at one side ofits horizontal path of travel, at the left hand side of the left handzone if commutator 38a is effective, at the left hand side of the middlezone if commutator 38b is effective or at the left hand side of theright zone if commutator 38c is efiective. As explained before, eachcathode ray tube screen may be said to have three display zones.

' The left hand zone being the zone for the highest order digit, theright hand zone for the lowest order digit and the middle zone for theintermediate order digit, that is, although the contact arm 62 isnegative with respect to the positive side of the battery 53, thebiasing networks including the resistors 59a or 59b, or 59c, establishsuch voltage conditions upon the deflector plates XL, XL so as to makethe terminal 51. just sufliciently positive or negative with respect tothe terminal 58 to maintain the electron beam in its extreme left handposition in-the related zone. The voltage on 51 is positive with respectto 58 to place the electron beam in the left'position in the left ormiddle zone and is negative with respect to terminal 58 to place theelectron beam in the left hand position of the right hand zone.

Consider the commutator 3811 effective with the illumination of cell 46Xdecreasing due to an increase in width of the opaque portion of thetrack. Under such conditions the negative bias on the grid of the tube52 decreases, resulting in an increase in plate current andcorresponding increase of the potential drop between the positive sideof the battery 55 and the contact 62. As a result the potential ofterminal 51 becomes less positive with respect to the terminal 58. The

' adjustments of the contacts 62 and 63b are prefrably such that thepotential between the terminals 51 and 58 become zero with the 38bcommutator effective for an illumination of the photo-cell which isintended to represent a positioning of the cathode ray beam in themiddle of its horizontal path. Decrease of the illumination beyond thispoint results in making the terminal 58. positive with respect to theterminal 51 until at the point of minimum illumination the cathode beamis deflected to its extreme right hand position in the middle zone.

It will be understood that a similar action so far as deflection of theelectron beam on the screen is concerned, takes place when commutator38a is effective or when commutator 380 is effective. It may bementioned, however, that when there is to be a display on the right handzone with commutator 380 effective a decrease in illumination causesterminal 51 to become increasingly negative with respect to terminal 58.

. Also when commutator 38a is efiective a decrease in illuminationcauses terminal 51 to become less positive with respect to terminal 58.

It will be understood that the amplifier and balancing circuitscontrolled by the photo-cell =i6Y are conveniently identical with thoseherein above described for the photo-cell 56x except a single biasingnetwork including batteries 50!], My, resistor 59: tap 63y is providedin lieu of the triple biasing network for the other photo-cell.

Accordingly, the vertical displacement or the 10 position of the cathoderay beam at any instant depends 'upon the controlling potentials appliedto both sets of deflecting plates XL. XR and YL, YU, the position of thebeam is directly controlled (through the instrumentality of theamplifier circuits described) by the amount of illumination 15respectively received by the photo-cells sex and Y. Thus as theillumination respectively received by these photo-cells varies duringrotation of the pattern component emitter, the oathode ray beam of anyone of the tubes traces a path to portray the particular digit charactercorresponding to the mainsegment and subsegment of the disk which isbeing scanned by the photo-cells. If the tracks of a sub-segment of themain segment portion pertaining to the digit 7 are being scanned, suchscanning so controls the illumination of the photo-cells that the tracks49X and MY respectively provide a predetermined variation in theillumination of the P oto-cells 45K and MY for each traverse ofasub-segment of the disk providing resultant corresponding variations indeflecting potentials on the plates of the cathode ray tube or tubes,whereby the cathode ray beam traces a path, in

this case, a path depicting the character 7 which is predetermined bythe main segment of the disk which is being scanned. As shown on Fig.9b, the lamps M and the motor 35 may receive current from a suitablesource 53 through a suitable switch 69. This current supply is alsoaflorded to a supplemental motor 35a, the purpose of which will besubsequently described.

The heater elements of the amplifying tubes 52 are preferably arrangedto receive current from a suitable source it upon closure oi switch ll55 (Fig. 9a). A battery 'lfi'll ig. 9a) afiords current supply for theheater elements of the cathode ray tubes upon closure of switch 13 (Fig.9a), suitable circuits extending from the battery and switch to theheater elements Ii of the various tubes (see Fig. 9b)

As is customary with cathode ray tube practlce, a biasing battery 14 isprovided. Such blasing battery is connected through suitable circuits toresistors 35 at each cathode ray tube. A 85 contact tap it on thisresistor connects to anode H (the number "1 anode of the cathode raytube). Adjustment of the contact tap on the resistor provides thefocusing adjustment of the electron beam. Also as is customary incathode ray tube practice, the commonly used deflector plates YU and XR.and the number 2" anode designated 15 are commonly connected to thepositive end of the resistor 15.

Before describing the keyboard switching control for the cathode raytubes, it may be again mentioned that if grid 53 of any one tube haswhich at each tube is shunted by resistors II and 18a. Cooperating withthe resistor 18 is a contact tap 19 which connects to the grid 3. Thepositive end of resistor 18a is connected back to the cathode heaterelement II. If both resistors 18a and 18 are in circuit with the battery11 the certain maximum negative bias previously mentioned will beapplied to the grid l3. 0n the other hand if resistor 18a is shunted out(in a manner tobe described) then this certainmaximum negative bias willbe reduced to allow implngement of the electron beam.

The application of maximum negative bias and the reduction of thismaximum negative bias for a particular tube or tubes is controlled fromthe 38 commutator devices previously mentioned. For example, if it isdesired to display the character 7, the brushes of the relatedcommutator 38 establish contact during the scanning of the '7 mainsegment of the disk 40 and with one of the commutators such as 38deflective the resistor its is shunted out, thereby allowing impingementof the electron beam with the resulting display of the character on thescreen. These shunting circuits will now be described in detail.

Keyboard and commutator wiring Referring now to Fig. 9a, which at thebottom of the figure shows the keyboard wiring, it will be noted thatthe contacts 2a 101- the units order keys are connected to a line 30Uwhich extends to one side of the SM commutator. The contacts 29 of thekeyboard pertaining to the tens order connect to a line 30T whichextends to one side of the ills commutator. The contacts 29 pertainingto the hundreds order connect to a line 3025 which extends to one sideofthe 38d commutator. The opposite sides of all of the commutators 33d,38c, 38! connect to a common line 82. At eacheathode ray tube the line32 connects to the negative end of the resistor 18a.

Referring again to Fig. 9a, the individual contacts 3i pertaining to the"9 keys are connected in common. to a transverse line which extends toone side of the 38-9 commutator. The 3| contacts pertaining to the "8keys connect to a transverse line which extends to one side of the 38-4commutator and so on. It will be under- .stood that an individualcommutator 38 is provided for each diflerent set of digital contacts 3!.The opposite sides of the set of commutators til-=9 to 38-4 connect to acommon line 83 which leads either through a supplemental commutator 8gor through a manually closed switch F to a line 8311 which extends (seeFig. 9b) to the positive or upper end of the resistor 18a.

It will be assumed that the number 425 is set up on the keyboard. Asshown by the timing diagram commutator 38d closes first, followed by 38cand 38f in the order named. As explained before, when SM is closed, thebeam impinges on the left hand zone of the screen, when 38c closes thebeam impinges on the middle zone of the screen and when 38) closes, thebeam is in the right hand zone. On closure of the number "4 commutatorof the 38 set, a circuit is completed from the positive end ofresistorlaa (Fig. 91)) via wire 83a, through switch F (Fig. 9a) nowassumed closed, to wire 83, through the number 4 commutator of the 38set, which closes at the cycle time shown in the timing diagram, throughthe number "4 key controlled contacts 29, 3! in the hundreds order,through the 38H line, through the 38d commutator to the line designated82 which goes to the negative end of resistor 18a (see Fig. 9b). Thisaction will completely shunt out the resistor 18a reducing the highnegative bias on grid l3 and allowing the beam to impinge upon thescreen l6 of each tube or tubes. Commutator 38a closes at the time shownin the timing diagram to cause the biasing network 68a, cm and 59a to beeffective to cause the character to be traced on the left hand zone ofeach tube. With the number 4 commutator of the 38 set efiective and the38d commutator efiective, the high negative bias on the cathode raytubes is reduced every time the photo-cells 46X and MY scan the 4asub-segment of the disk 48. With such high negative bias so reduced, thepotential of terminal 51 (Fig. 9a) will be applied through a line 81 andwires 88 to the XL plates of the various cathode ray tubes. The XE.plates of the various tubes are connected back to the 58 terminal viawires 89 and line 98. Accordingly, the variations in potential acrossthe terminals 51 and 58 will be applied to the XR and XL plates. The Youtput terminal 68 connects to line 9|, which connects to wire 92leading to the YL deflecting plates. The YU deflecting plate isconnected back to the 6! terminal through the wire 88 and line 98. Inthis way the Y deflecting voltages are applied to the YU and YL plates.This application of potentials to the deflecting plates of the varioustubes will display 4 in the left hand zone of all the tubes.

The control circuits for the tens order display will now be traced. Withthe number 2 key depressed in the tens order on the keyboard, a circuitwill be completed from the positive end of resistor 18a (Fig. 9b) towire 83a, thence through switch F (Fig. 9a) now closed, to wire 83. Uponclosure of the number 2 commutator of the 38 set, a circuit will becompleted through the number 2 key controlled contacts 29, 3| in thetens order to common line 38T and upon closure of the 38c commutatorthis circuit will be completed to line 82 which extends over to thenegative end of the 1811 resistor. This circuit so completed will shuntout the 18a resistor and will remove high negative bias from the grid 13of each cathode ray tube, thereby permitting an electron beam to impingeupon the screen of each tube in the center zone. The deflecting voltagesare applied to the XL, XR, YL and YU plates in a similar manner asbefore explained, except that in this instance such deflecting voltageswill be applied at the time when the photo-cells are scanning the number2b sub-segments of the disk. At this time it will be recalled that the38b commutators screens thereof. Such display will be in the right handzone due to the timing of the 380 commutator. The deflecting voltageswill be applied to the plates of the various tubes when thephotoelectric cell is scanning the 50 sub-segment of the disk.

In some cases it may be desirable to have the display devices flash thenumbers instead of displaying them continuously. When it is desired tooperate the apparatus with such flashing display, the operator opens theswitch F (Fig. 9a). Referring to Fig. 3, it will be noted that the smallmotor 350. drives a commutator 38g. The brushes 39g with motor 35a inoperation intermittently high negative bias on the grids l3 of thecathode ray tubes for a certain periodand remove it for anotherperiod.For example, the commutator might be arranged to close the circuit forhalf a second and interrupt it for half a second. This would provide forone-half second flashing display of the numbers by the variousdisplaying units.

Summarizing, the operation of the main embodiment may be explained asfollows: The general purpose of the 38-0 to 389 commutators is to removehigh negative bias from the grids l3 of the difierent cathode ray tubes.Depending on the time when a particular commutator closes which iscoordinated to the disk track main segments the related character willbe displayed on the screen of the tube or tubes. The purpose of the 38a,38b and 380 commutators is to selectively render the three biasingnetworks efi'ective to cause tracing either in the left hand zone, themiddle. zone or the right hand zone. As shown in the timing diagramthe38a commutator closes first and the closure of this commutator circuitis concurrent with the closure of the 38d commutator pertaining to thehundreds order section of thekeyboard. Accordingly, the hundreds orderdigit will be displayed on the left hand zone of each tube or tubes..Following the closure of the 38a and 38d commutators there is aconcurrent closure of the 38b and 386 commutators. This affords displayof the tens order digit in the middle zone of each tube. Following thisthere is a concurrent closure of the 380 commutator and the38f'commutator which affords a concurrent display of the units orderdigit on the right hand zone of each tube.

According to the modified embodiment of the scription of Fig. 3 ismodified in the following manner. The previous shaft 31 is now splitinto two sections, viz. sections 31 and 31a (see Fig. 13)

Three-to-one gearing 36a drives the 31 shaft section which in turndrives .the 38 commutatorsand the disk or rotatable control element 48a.One-to-one gearing 3% drives the 310. commutator drive shaft with aone-to-one drive ratio. Shaft 31 makes three revolutions during onerevolution of shaft 31a. Fixed on the shaft 31 are ten commutators, eachof which is'generally designated 38. One of'these commutators isprovided for-each digit 1 to 9 with a further commutator'being providedfor zero. Each of the commutators 38 (see Fig. 9aa and timing diagramFig. 10cc) comprises an insulated portion for the greater portion of theperiphery of the commutator with a conducting portion at a single pointon the commutator. Trailing on the periphery of each commutator is apair of brushes which are generally designated 39 on Fig. 13. Theconducting segments of the 38 set of commutators are so arranged toclose at different angular positions of rotation of the shaft 31 as willbe readily understood by inspection of Fig. 9nd and the lower portion ofthecommutator timing diagram shown in Fig. 10nd.

Shaft 31a. is adapted to drive six commutators 38A, 38B, 38C; 3813, 38F.and 38F. Each of these last mentioned commutaiors have conductingportions adapted to close their commutator controlled circuit forone-third of a revolution for each commutator. This will be clear byreferring to the commutator timing diagram Fig. 10m, upper portion. onthe conducting portions of these latter commutators are pairs ofbrushes, one pair of which is designated 39a in Fig. 3. The purpose ofthe commutators 38A to 38F inclusive, and their timing will besubsequently further explained.

According to; the modified embodiment of the invention, the trackconfiguration of the rotatable control element is modified, In lieu ofthe disk shown in Fig. 5, which disk has main segment sections andsub-segment sections, the disk 30a which is used in the modifiedembodiment of the invention comprises main segment sections only. Theconfiguration will be obvious from an inspection of Figs. 11 and 12wherein it will be noted that the main section is identical inconfiguration with a sub-section of the previous disk except that it isextended over a greater are. In other words, in place of having a mainsection with three sub-sections, a main section only is utilized and thetrack configuration in the main section is like the track configurationof the sub-section except that the track sections of the main sectionoccupy 36 degrees of arc instead of 12 degrees of arc as in the mainembodiment.

According to the modified embodiment, commutators 38A, 38B and 380function in an identical manner for controlling their associated biasingnetworks as commutators 38a, 33b and 38c in the main embodiment.However, the timing of such modified commutators is difierent as will beclear by referring to the timing diagram (Fig. 100). commutator controldevices 38D, 33E and 38F also function in a similar manner tocommutators 38d, 38c and 38! in the main embodiment.

By referring to the timing diagram (Fig. 1041a) it will be noted thatthe commutators 38A and 38D make first and their circuits areestablished for one-third of a revolution of these commutators. Duringthis same one-third of a revolution the commutators 88-4] to 38-9inclusive and the disk 40a rotate through a complete revolution andduring this complete revolution any one of the digits or 0 can be tracedupon the screen of the tube. The tracing will be in the left hand zonedue to the network control afforded by the commutator 88A and -by thecolumnar control afforded by the 881) commutator. In the followingone-third of a revolution of the commutators on the shaft 310, thecommutators 88A and 38Dopen their circuits and commutators 38B and 38152close their circuits. During the one-third of a revolution when theselatter circuits are closed, the 38-0 to 38-8 commutators and the disk40a again rotate through a complete revolution to afford proper tracingcontrol for the display of any digit or digits. The dlspleywill beofthedigits inthe tens order due to commutator ME and will be in themiddle zone due to commutator 88B rendering the middle biasing networkeffective. The

action for the following one-third of a revolution embodiment may beexplained as follows: The

general purpose of the 38-0 to 38-9 commutators is to remove highnegative bias from the grids 13 of the difierent cathode ray tubes.Depending on the time when a particular commutator closes which iscoordinated to the disk track segments the related character will bedisplayed on the screen of the tube or tubes. The purpose of the 38A,38B and 38C commutator-s is to selectively render the three biasingnetworks effective to cause tracing either in the left hand zone, themiddle zone or the right hand zone. As shown in the timing diagram (Fig.10cm) the 38A commutator closes first and the closure of this commutatorcircuit is concurrent with the closure of the 38D commutator pertainingto the hundreds order section of the keyboard. Accordingly, the hundredsorder digit will be displayed on the left hand zone of each tube ortubes. Following the closure of the SBA and 38D commutators, there is aconcurrent closure of the 8813 and 38E commutators. This aflords displayof the tens order digit in the middle zone of each tube. Following thisthere is a concurrent closure of the 38C commutator and the 38Fcommutator which affords a concurrent display of the umnits order digiton the right hand zone of each According to the main embodiment thepossible display of characters from the disk 40 for one completerotation of the rotatable control element or light modifying disk may bestated to be as follows: 7

According to the modified embodiment the possible display of charactersfrom the disk or light modifying rotatable element 40a for threecomplelte revolutions thereof may be stated to be as 20 ows:

What is claimed is:

1. A character outline displaying apparatus including a single cathoderay tube having a screen upon which character outlines are traced anddisplayed, said cathode ray tube having electron deflection controlelements, a common source for generating the changing potentials to beimpressed upon the deflection control elements for deflecting anelectron beam and for controlling the possible tracing of a set ofdifferent character outlines, means for selecting which characteroutline or outlines are to be displayed upon the screen under control ofthe source means, a plurality of supplemental biasing controls for ap-2,281,350 lines may be traced and displayed upona single screen of asingle tube.

2. A character outline displaying apparatus including in combination, asource of varying potentials for controlling the deflection of anelectron beam in a cathode ray tube whereby the latter may variablytrace different character outlines, a single cathode ray tube having ascreen and having deflection control elements connected to receive thevarying potentials from said source to cause the electron beam to tracea character outline upon the screen thereof, a plurality of biasingcontrol devices for applying changed biasing voltages to the deflectioncontrol elements which receive varying tracing potentials, and timingmeans for bringing said biasing control devices into action successivelyfor effecting successive supplemental displacement of the electronbeamto various lateral zones of plates and a screen, a source of varyingpotentials for controlling deflection of an electron beam in saidcathode ray tube to control tracing of character outlines and afiorddisplay of character outlines on the screen thereof, said sourceincluding a rotatable control element, means to repeatedly rotate saidelement; and including in combination, supplemental source meansafford-- ing a plurality of different supplemental biasing voltages forapplication to certain of the deflecting plates of the tube, saidcertain of the deflecting plates also receiving the varying tracedcontrolling potentials from the first mentioned source, and meansoperative upon successive rotation of said element for selectivelyconnecting said supplemental source means to the deflecting plates ofthe tube to selectively change the supplemental biasing voltage thereonso that upon 5. A cathode ray character displaying apparatus with acathode-ray tube havingdeflecting plates and a screen, a source ofvarying potentials for controllingdefi'ection of an electron beam insaid cathode ray tube or tubes to control tracing of character outlinesand afford display of character outlines on the screen thereof, saidsource including ta rotatable control element, means to rotate andangularly displace said element; and including in combination,supplemental source'means affording a plurality of difierentsupplemental biasing voltages for application to certain of thedeflecting plates of the tube, said certain of the deflecting platesalso receiving the varying traced controlling potentials from the firstmentioned source, and means operative upon displacement of the aforesaidelement to variable angular positions during one revolution thereof forselectively connecting said supplemental source means to the deflectionplates of the tube to selectively change the supplemental biasingvoltage thereon so that upon successive angular displacement of theelement during one revolution thereof character outlines are tracedunder' the control of the element and displayed at difiere'nt laterallyspaced zones on the screen of the cathode ray tube under control of theconnected supplemental biasing source means.

6. A number displaying apparatus according to claim 2 wherein the timingmeans for bringing the biasing control devices into action com prisecommutator devices which rotate in synchronism with a rotatable element,said rotatable element comprising the control element for the source ofvarying potentials.

7. A number displaying apparatus according to claim 2 wherein the sourceof varying potentials includes a rotatable control element and whereinthe timing means includes commutators rotating in time with the controlelement and establishing control circuits for the biasing controldevices during successive revolutions of the control element.

8. A number displaying apparatus according to claim 2 wherein the sourceof varying potentials includes a rotatable control element and V whereinthe timing means includes a set of comsuccessive rotation of the elementcharacter outlines are'traced under control of the element and displayedat different laterally spaced zones on the screen of the cathode raytube under control of the connected supplemental biasing source means.

mutators rotating in synchronism with the control element forsuccessively establishing different control circuits for the biasingcontrol devices during a single revolution of the control element. k

' JAMES W. BRYCE.

